Is coarse sand good as ground cover for tank?

Good morning,

Here are a couple of photos of my axolotls.
I am looking at putting them into a bigger tank 2.6ft. I have some left over coarse sand (suitable for adding to concrete, mixing mortar, propagating mix & succulent & underlaying for paving). I was just wandering if I can use it in the bottom of the tank (after a good clean of course).

Also you can see that the axolotl at the back has her gills (i think it is a girl but that is another question for later!!) are really forward since I put the little axolotl in her tank yesterday. I was just wondering if it has any significance?

Thank you

You may get more responses posting this in the axolotl section of this forum.

Personally, after having a bad experience, I would steer clear of coarse sand. I used aquarium sand in my tank originally thinking it was fine enough but then had issues with one of my axolotls ingesting it. Also I am not sure if there are any additives to the sand used for cementing purposes?

I now use play sand which is much finer. I used Richgro play sand which you can get at Bunnings of Home Hardware and sieved the bits of gravel out whilst washing it and it is very fine and looks great. It was only about $8-9 a bag so quite cheap.

Gills curled far forward can suggest they are stressed. Another sign is a curled tail. Though I believe the gills are normally further forward than yours when stressed. But she could just be settling into the new environment and will settle in soon and probably nothing to worry about. Is the tank cycled? What are the parameters - ammonia, nitrite, nitrate, PH and temperature?